Andrew l



(No Model.)

A. L. BIKER. CARBON BRUSH AND HOLDER THEREFOR.

Patented July 7, 1891.

@ affi w Wzllhemesx UNITED STATES PATENT OFFICE.

ANDREIV L. BIKER, OF NEIV YORK, N. Y.

CARBON BRUSH AND HOLDER THEREFOR.

SPECIFICATION forming part of Letters Patent No. 455,518, dated July'7', 1891.

Application filed March 25, 1891.

T0 ctZZ whom it may concern.-

Be it known that I, ANDREW L. BIKER, a resident of New York city, countyand State of New York, have invented a new and useful Improvement inCarbon-Brush Holders, which improvement is fully set forth in thefollowing specification.

This invention relates to the construction of holding devices for carbonbrushes. Many devices of this sort have been contrived heretofore; butthose with which I am acquainted are complicated and costly.

The object of this invention is to produce a simple device which willhold the carbon brushes against the commutator with yielding pressure,making a good electrical contact therewith.

The inventionincludes the use in a dynamo or electric motor of a brushcomposed of two carbon plates or bars bearing at their ends against thecommutator-plates. I'Ieretofore the brush has been made of a single baror piece of carbon. I have found by trial that in the use of carbonbrushes the ends of the two pieces held together wear in such a way asto preserve a much better electrical contact and produce much lesssparking than when the brush is composed of a single carbon piece.

The accompanying drawings, which form part of this specification,illustrate a holder for carbon brushes constructed in accordance withthe invention, Figure I being a crosssection, and Fig. II a sideelevation, of a brush and its holder.

The holder consists of a rectangular mortised piece or frame A, throughwhich pass vthe carbons B B, and in which they fit with a thumb-nut G.

snugly. This frame has at one side a shank or arm C, terminating in ascrew'c, by which the holder is bolted to the usual rocker-arm, whichsupports the brushes. Frame A has two laterally-projecting lugs a, oneon each side, from which spring the upright rods D E.

F is a cap which fits tightly over the ends of the carbons, and it hastwo perforated lugs f, through which the guide-rods D E pass loosely.Rod D-is prolonged and is screw threaded at its upper end for engagementA spiral compression- Serial No. 386,374. (No model.)

spring (1 surrounds rod D and passes downwardly upon lug f of the cap.

I11 order to keep the carbons from rattling or separating, a spring-gibor cushion b is placed in the frame A.

As carbon brushes have no elasticity, they cannot be held against thecommutator obliquely, as usual, with metal brushes. Moreover, if soheld, they would be in greater danger of breakage. Consequently carbonbrushes are mounted and held against the cylindrical commutator at rightangles to the tangent, as indicated in Fig. I, in which the dotted arcrepresents the outline of the commutator-surface.

Instead of using one carbon plate, I employ two plates 1 B, which areplated with metal (preferably copper) and held in contact, the plane ofseparation being parallel with the armature-shaft. I have found thisarrangement of great advantage, in that it diminishes considerably thesparking, which takes place as the circuits of the coils, shortcircuitedwhen the brush spans two adjacent commutator-plates, are successivelybroken.

The spring (Z presses the cap F downward and keeps the ends of thecarbons against the commutator-strips. As the carbons wear Off and thespring becomes relaxed it may be tightened by screwing down the thumbnutG.

I claim as my invention 1. A holder for the carbon brushes of a dynamoor motor, comprising a mortised frame or box, through which the brushpasses, two upright guiderods fastened to said frame, a cap fitting overthe end of the brush and movable 011 said guide-rods, a springsurrounding one of the rods and bearing on said cap, and anadjusting-nut on said rod, substantially as described.

2. The combination of a mortised frame adapted for attachment to therocker-arm or support of the brushes and provided with an interiorspring-gib or cushion, two upright guide-rods attached to said frame, acap titting the top of the brush and having openings through which saidrods pass loosely, a spring bearing on said cap, and an adjust ing-nut,substantially as described.

3. In coinbinationwith a holder adapted to In testimony whereof I havesigned this present the end of a carbon brush radially specification inthe presence of two subscrib- IO against the cylindrical surface of the00111- ing witnesses.

nintator, a brush composed of two pieces 01' 5 plates of metal-platedcarbon placed with ANDREXV BIKER their adjacent surfaces in contact, theplane \Vitnesses: of separation being parallel with the commu- PERRY J.FULLER,

tator-strips, substantially as described. CHARLES M. KIRBY.

